Russian troops attempted to take a Ukrainian military base by storm on the Crimean peninsula soon after dark on Friday, ramming the gates with a truck and rushing inside. Within two hours, the Russian forces managed to seize part of the Ukrainian air force base at the edge of Sevastopol, the city that also houses Russia’s Black Sea naval fleet. But after failed negotiations for the surrender of the entire base, the Russian troops pulled back before midnight.

“The base is now back in full control of the Ukrainian armed forces,” said a spokesman for the Ministry of Defense, asking to remain anonymous. Armed pro-Russian paramilitaries in civilian clothing were still in the area, the spokesman said, but the two Russian military trucks that had rammed the gate of the A-2355 base outside Sevastopol were gone, as were the several dozen Russian troops involved. “Now only the radicals are left,” he said, referring to the pro-Russian militants who call themselves “self-defense forces” on the Crimean peninsula.

A group of journalists from a Ukrainian television channel had been badly beaten by these military irregulars, who guarded the perimeter of the base while the Russian troops were attempting to seize it by force, the Ministry spokesman said. “Some of the reporters are still missing,” he added. “We are trying to find where they are.”

Late on Friday evening, Colonel Viktor Kukharchenko, the deputy commander of another Ukrainian air force base in Crimea, told TIME that the “attack is on” when Russian forces began streaming through the gate and demanding the Ukrainian forces surrender. No shots appear to have been fired in the course of the raid, Kukharchenko said, and the Ukrainians refused to give up their positions.

Before Friday’s attack, Russian forces have been satisfied to surround all of the Ukrainian bases in Crimea and barricade their servicemen inside. By slamming through the gates with a military vehicle, the Russian forces initiated an escalation of the ongoing conflict over Crimea between Russia and Ukraine that could easily have led to bloodshed and a full-scale war. It not was immediately clear why the Russians withdrew.

At the time of the attack, roughly 100 Ukrainian troops were inside the base, which houses a reserve command center for anti-aircraft defenses on the Crimean peninsula, the spokesman for the Defense Ministry said. Kukharchenko, an air force colonel at the nearby base of Belbek, said that the forces who attempted to seize the base included Russian servicemen not wearing any identifying insignia, as they have refused to do throughout the weeklong occupation of Crimea by Russian forces.

Russian President Vladimir Putin has denied that his military has been surrounding Ukrainian bases in Crimea since the end of February, even though the vehicles of the occupying force have Russian license plates and some of its officers have told reporters they are from Russia.